Abstract: To take account of the practical difficulties for measuring the sideslip and roll angles of a vehicle and the vehicle is always subject to a large range of uncertainties because of external disturbances, an optimal control strategy for a four-wheel steering (4WS) vehicle is proposed, which is based on a reduced-order observer control model. Feedback control system is designed using optimal control theory to enhance the disturbance handling stability of the vehicle, and the simulation of disturbance handling stability with high vehicle speed is performed. The results show that the reduced-order observer has the excellent characteristics in the considered speed range in tracking path and so the control system has fine dynamic characteristic and strong robustness, and the 4WS vehicle with the proposed control strategy can provide greater disturbance resistance ability.

Key words: Disturbance, Four-wheel steering (4WS), Handling stability, Reduced-order observer, Vehicle, In-situ inspection, Partial Least-Squares Regression, Regression analysis, Error compensation, Key words: Precision Machining